1. Field of the Invention
The invention relates to a method and instruments to perform a percutaneous lumbar diskectomy.
2. Description of the Prior Art
Many people suffer from lower back pain in the lumbar region of their spines caused by a herniated or protruding lumbar vertebral disc which is often called a slipped disc. Spinal discs are shock absorbing cushions between spinal vertebrae. FIG. 1 shows a schematic view of a typical disc 1 sandwiched between two vertebrae 2. The disc has a fibrous capsule or annulus 3 which surrounds a cartilage-like nucleus 4 that has a consistency similar to a raw potato. Discs are avascular, that is, they have no blood vessels. In a herniated or bulging disc, there are small tears in the disc capsule which allow the nucleus material to bulge and expand around the tear. If the bulge contacts spinal nerves, the person may experience extreme shooting pain in his back or legs.
A slipped disc is treated by eliminating nerve contact. It has been found that bed rest and spinal traction may alleviate the pain in simple cases. In more serious cases, a portion of the affected disc nucleus has been surgically removed, which relieves the disc bulge, in a procedure known as a laminectomy.
Since the disc is confined within the spinal column, it must be accessed in order to remove nucleus material. In a laminectomy, nucleus access is obtained by cutting a channel from the rear of the patient's back through the vertebral lamina to the disc. A long incision of the order of six inches is made through the skin and fat layer to the lamina. The incision eventually heals as an unattractive scar. The surgeon cuts through the lamina and retracts body tissue including spinal nerves and blood vessels located around the dural sac 5 (a conduit for the nerves), ligaments and major back support muscles. Once the channel is cleared, the surgeon cuts a hole into the disc capsule through which he passes instruments in order to remove a portion of the disc nucleus. The procedure is normally performed in about one and one-half hours, while the patient is under general anesthesia.
In known laminectomy procedures, the surgeon does not visually inspect the nucleus removal because he is removing the material by feel. Since instruments are blindly inserted through the hole, very occasionally they overpenetrate through the other side of the disc and damage other tissue structure.
A laminectomy is a very destructive process. Cutting lamina and retracting spinal nerves, blood vessels, muscle and ligaments often leads to permanent scarring which may cause more permanent pain than the original slipped disc. Many people prefer to continue suffering pain caused by the herniated disc rather than risk permanent pain from the laminectomy. Laminectomies also require long hospitalization and hence postoperative recovery periods, typically from one to two months, if there have been no complications caused by the operation.
In the past, other procedures have been developed in order to alleviate disc herniation. One procedure was to inject a nucleus dissolving chymopapain enzyme into the disc with a spinal needle to relieve the pressure on the nerves. The United States Food and Drug Administration banned the use of chymopapain enzyme for this procedure in the mid-1970's. Clinical testing raised doubts concerning its effectiveness and its significant complications due to tissue reaction to the enzyme.
Another known procedure is a microsurgical diskectomy. As in a laminectomy, the disc is accessed by cutting a channel from the rear of the patient's back to the disc. However, by using a smaller incision and visual magnification with an operating microscope or operating loupes, small diameter microsurgical instruments can pass between the vertebral laminae without bone cutting and into the disc. Blood vessels and nerves are still retracted. Scarring and post operative pain is reduced, but not eliminated.
There has thus been a long felt need in the medical profession to reduce the cost, risk, pain, and recovery time of diskectomies. All of these drawbacks are materially reduced by performance of a percutaneous lumbar diskectomy disclosed herein.